where \(r = \Vert \mathbf {x} - \mathbf {c}\Vert \)  with \(\mathbf {x}\)  and \(\mathbf {c}\)  the evaluation points and the radial basis center respectively. \(\epsilon \)  is a scalar shape parameter that in this case is set \(\epsilon = 1.0\) . This function is conditionally positive definite provided that the order of the monomial is at least equal to 2 [1]}, [2]}. Therefore, in order to ensure the uniqueness of the solution we have chosen to use \(m=2\)  in expression (REF ).
<FIGURE><FIGURE>